StubWindowMetricsCalculatorRule.kt
/*
* Copyright 2021 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package androidx.window.testing.layout
import android.app.Activity
import androidx.window.core.ExperimentalWindowApi
import androidx.window.layout.WindowMetricsCalculator
import org.junit.rules.TestRule
import org.junit.runner.Description
import org.junit.runners.model.Statement
/**
* A [TestRule] that will sub out the actual [WindowMetricsCalculator] with a more simple one that
* will support testing independent of the current platform. The fake [WindowMetricsCalculator] that
* is used will return the width and height from the [android.util.DisplayMetrics] associated to
* an [Activity]. The result of [WindowMetricsCalculator.computeCurrentWindowMetrics] and
* [WindowMetricsCalculator.computeMaximumWindowMetrics] will be the same. For accurate results use
* the Espresso Test framework with an actual [Activity] and use the actual
* [WindowMetricsCalculator].
*/
@ExperimentalWindowApi
class StubWindowMetricsCalculatorRule : TestRule {
override fun apply(base: Statement, description: Description): Statement {
return object : Statement() {
override fun evaluate() {
WindowMetricsCalculator.overrideDecorator(StubMetricDecorator)
try {
base.evaluate()
} finally {
WindowMetricsCalculator.reset()
}
}
}
}
}